Investment Securities (Summary Of Available For Sale Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 3,089,688	[1]		$ 2,931,630	[1]
Gross Unrealized Gains	22,330			54,116
Gross Unrealized Losses	(34,312)			(4,634)
Fair Value	3,077,706		2,981,112	2,981,112
U.S. Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	357	[1]		356	[1]
Gross Unrealized Gains	0			0
Gross Unrealized Losses	0			0
Fair Value	357			356
U.S. Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	35,049	[1]		35,791	[1]
Gross Unrealized Gains	1,476			2,255
Gross Unrealized Losses	(229)			0
Fair Value	36,296			38,046
Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	186,489	[1]		289,523	[1]
Gross Unrealized Gains	1,598			3,787
Gross Unrealized Losses	0			0
Fair Value	188,087			293,310
Mortgage-Backed Securities Issued By U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	209,001	[1]		238,381	[1]
Gross Unrealized Gains	2,963			7,220
Gross Unrealized Losses	(2,403)			(8)
Fair Value	209,561			245,593
Mortgage-Backed Securities Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,319,412	[1]		1,832,076	[1]
Gross Unrealized Gains	13,576			37,646
Gross Unrealized Losses	(27,637)			(2,229)
Fair Value	2,305,351			1,867,493
Collateralized Mortgage Obligations Issued By U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	321,971	[1]		513,637	[1]
Gross Unrealized Gains	1,147			2,534
Gross Unrealized Losses	(3,603)			(1,682)
Fair Value	319,515			514,489
State And Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,761	[1]		15,218	[1]
Gross Unrealized Gains	265			582
Gross Unrealized Losses	(2)			(2)
Fair Value	11,024			15,798
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,648	[1]		3,648	[1]
Gross Unrealized Gains	1,305			92
Gross Unrealized Losses	0			0
Fair Value	4,953			3,740
Other Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,000	[1]		3,000	[1]
Gross Unrealized Gains	0			0
Gross Unrealized Losses	(438)			(713)
Fair Value	$ 2,562			$ 2,287

[1] Amortized cost is adjusted for other-than-temporary impairment charges, which have been recognized in the consolidated statements of income